=head1 NAME

Tangram::Type::Scalar - map scalar fields

=head1 SYNOPSIS

   use Tangram;

   Tangram::Schema->new(
      classes => { NaturalPerson => { fields => {
         string => [ qw( name firstName gender ) ],
         int => [ qw( age ) ],
         real => [ qw( height weight ) ],

   $schema = Tangram::Schema->new(
      classes => { NaturalPerson => { fields => {
         string =>
         {
            name    => { sql => 'VARCHAR(100)' },

            1stname => {
               col => 'firstName',
               sql => 'VARCHAR(100) NULL' },

            gender    => undef()
         },

=head1 DESCRIPTION

Classes Tangram::Type::String, ::Int and ::Real and ::Ref are responsible
for mapping the various subtypes of scalars. The first three mappings
are documented here since they differ very little. See L<Tangram::Type::Ref::FromMany>
for information on mapping references.

Tangram::Type::String uses DBI's quote() method to quote strings if that
method is available, thus making it possible to store binary objects
or multiline text in databases that support it (thanks to Marian Kelc
<marian.kelc@ruhr-uni-bochum.de> for suggesting this improvement).

The three predefined typetags C<string>, C<int> and C<real> are for
the corresponding Perl scalar subtypes.

Each scalar field is stored in a single column of the table associated
to the class.

The persistent fields may be specified either as a hash or as an array
of field names.

In the hash form, each entry consists in a field name and an
associated option hash. The option hash may contain the following
fields:

=over 4

=item * col

=item * sql

=item * automatic

=back

C<col> sets the name of the column used to store the field's
value. This field is optional, it defaults to the persistent field
name. Override if the field name is not an acceptable SQL column name.

C<sql> sets the SQL type of the column. Used by Schema::deploy() when
initializing a database. Defaults to 'VARCHAR(255) NULL' for strings,
'INT NULL' for ints and 'REAL NULL' for reals.

C<automatic>, if set to true, tells Tangram not to save the field to
storage. This is useful for auto-increment or timestamp columns.

The persistent fields may also be specified as an array of strings, in
which case the defaults are used.